MQTT IoT智能插件Python

Question

我是物联网的新手，我的大学有一个代码练习。我不知道如何连接此脚本，以便连接到MQTT并在没有错误的情况下运行

如何连接MQTT？脚本如下所示：

import paho.mqtt.client as mqtt
import ssl
import os
import sys

import matplotlib.pyplot as plt
from matplotlib.widgets import Button
from threading import Timer
from datetime import datetime

class IoTExample:
    def __init__(self):
        self._establish_mqtt_connection()

    def start(self):
        self.client.loop_forever() 
    
    def disconnect(self, args=None):
        self.client.disconnect()

    def _establish_mqtt_connection(self):
        self.client = mqtt.Client
        self.client.on_log = self._on_log
        client.username_pw_set('iotlesson', 'YGK0tx5pbtkK2WkCBvJlJWCg')
        self.client.connect('phoenix.medialab.ntua.gr', 8883)
        client.subscribe('hscnl/hscnl02/state/ZWaveNode005_Switch/state')
        self.client.publish('hscnl/hscnl02/sendcommand/ZWaveNode005_Switch', 'ON')
        self.client.loop_forever()

    def _on_connect(self, client, userdata, flags, rc):
        self.client.on_connect = self._on_connect

    def _on_message(self, client, userdata, msg):
        self.client.on_message = self.on_message
        print(msg.topic+' '+str(msg.payload))

    def _on_log(self, client, userdata, level, buf):
        self.client.on_log = self._on_log
        print('log: ', buf)

try:
    iot_example = IoTExample()
    iot_example.start()
except KeyboardInterrupt:
    print('Interrupted')
    try:
        iot_example.disconnect()
        sys.exit(0)
    except SystemExit:
        os._exit(0)

我得到了以下错误：

python /home/mina/paho.mqtt.python/iot_example.py
Traceback (most recent call last):
  File "/home/mina/paho.mqtt.python/iot_example.py", line 41, in <module>
    iot_example = IoTExample()
  File "/home/mina/paho.mqtt.python/iot_example.py", line 13, in __init__
    self._establish_mqtt_connection()
  File "/home/mina/paho.mqtt.python/iot_example.py", line 24, in _establish_mqtt_connection
    self.client.connect('phoenix.medialab.ntua.gr', 8883)
TypeError: unbound method connect() must be called with Client instance as first argument (got str instance instead)

Answer 1

   def _establish_mqtt_connection(self):
        self.client = mqtt.Client()

创建Client实例时需要添加括号

TypeError: unbound method connect() must be called with Client instance as first argument (got str instance instead)

它说unbound这一事实表明您没有创建实例。相反，self.client只是Client类本身的另一个名称